In hog breeding, there is always the problem of the dam crushing the newly born shoat when the frequently very heavy dam lies down or when, while lying down, she changes from one position to another. Up to now, there have been many attempts to provide structures to prevent this crushing of shoats, the said structures being known as shoat protecting cages. In spite of these cages, it is always possible, especially during the first three to six days after the birth, for the shoats to stray under the moving dam.
Attempts have also been made to solve this problem by providing a source of heat in an area of the farrowing pen remote from the dam, in order to induce the shoat to move away from the dam to this warm area and to remain there. This has been partly successful but, since the shoats naturally wishes to suck from the dam, and are unquestionably attracted by the dam's odor, this idea is only partly satisfactory.
Extensive investigations in the European Common Market have shown that in shoat raising operations equipped with the best protective devices known today, there is still a 6.2% loss due to crushing of the shoats.